Custom error pages in Symfony

We all know the annoying guy in the image. It tells us that something went terribly wrong. In order to see him as little as possible, I have become a control freak : I check everything in the Controller. Even the things that I know are not supposed to happen. But if someone tampers with some data in the database and those never-to-happen things do occur ? I mean, everyone has seen famous mysql errors on big important websites. So bad data does happen. So in order to handle all my this-code-should-not-be-reached tests gracefully, I have a custom made error page.

The setup is quite simple actually : inside my views folder, I create a special folder named Error , and inside it I place this file : raise_custom_page_error.html.twig . I usually make this template a standalone file, meaning that Symfony can load it without needing any other main template. The main error displaying is done by the following code :

<div class="middle-box text-center">
    <h1>#42</h1>
    <h3 class="font-bold">Error</h3>

    <div class="error-desc">
        The server has encountered an error. 
        <br>
        Code : {{ error_number }}
        <br><br>
        <a href="{{ path("cookiejar_go_to_jail_do_not_pass_go") }}" class="btn btn-w-m btn-danger">Home</a>
    </div>
</div>

Now, whenever I have some test in the Controller which should never test false, I call my error template like this :

<?php

if ($cookieJar->getCookies() === null)
{
    // This should not happen
    // Do some error logging also ...
    
    // Send user to custom_error_page
    return $this->render(
        'CookiejarBundle:Error:raise_custom_page_error.html.twig',
        array (
            'error_number'		=>	'3141592',
        )
    );
}

That’s all it takes. The result is something like this :

 

I have also discovered this technique to be useful when in development mode also. Sometimes when I am on big projects, it happens that I accidentally create incoherent data when testing. And each time this #42 pops out, I can copy the error code, do a quick search inside my project and find the culprit.

I hope this is useful 😉

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